Since a map display in a conventional navigation device displays uniformly all roads including unnecessary roads for route guiding, especially, in a high region in road density such as inner city, the overall screen becomes complex, which results in a factor to reduce considerably momentary visibility thereof.
As a scheme for resolving the foregoing problem, there exist a variety of conventional technologies for eliminating unnecessary information for route guiding from the screen, or for making inconspicuous such information by changing display colors. A conventional technology disclosed in Patent Document 1 displays in a toned down manner the periphery excluding a circle of a given radius around the present location. In this case, both minor streets and arterial roads are uniformly toned down. A route to a notable facility existing at a location beyond the given radius is not toned down.